httpd | This is the Apache executable file. |
httpd.conf | This is the main configuration file. It contains the variables that specify server-specific configuration information. |
srm.comf | srm stands for Server Resource Management. Historically, this file contained the variables that specifed how server resources were to be used. These days, you will usually find all directives in the httpd.conf file. |
access.conf | Historically, this file contained the variables relating to access control. These days, you will usually find all directives in the httpd.conf file. |
apachectl | A script used to stop, start, and restart Apache. |